a. Field of Invention
This invention relates to a casing scraper, that is a tool for use in a wellbore to scrape debris from the interior of the wellbore casing.
b. Description of Related Art
In wellbore clean-up and mud displacement operations it is well known to use a casing scraper to remove debris from the interior surface of the casing. Casing scrapers may be non-rotating (that is there is substantially no rotation of the casing scraper relative to the casing) or may be rotating (in which case the scraper is forcibly rotated relative to the casing to increase the scraping action). In many clean-up operations, particularly on newly cased wells, non-rotating scrapers are preferred because of their relatively less aggressive scraping action. However, in other clean-up operations a more aggressive action produced by rotating the scraper at, for example 40-120 rpm is preferred.
Scrapers are available from a number of commercial sources, and the present invention provides an improved design in this type of tool.